What to Cut Back in Fall

As a new gardener I get confused trying to decide what to cut back in the fall and how far back to cut. The plants I am most concerned about are the hydrangeas, hibiscus, a variegated Fallopia and a dwarf Little Henry Sweetspire. I also have fountain grass, which for the first time I planted in the ground rather than a pot. Can I cut this back to re-grow next year and how far down do I cut?

I am a big fan of leaving things stand for winter. Many plants provide food and shelter for the birds and overwintering sites for butterflies and other beneficial insects. Plus by the time March rolls around most of us are anxious to get out in the garden. The white round flowered hydrangeas can be cut back to the ground in fall or spring before growth begins. Only prune the panicle hydrangeas if needed. And wait until spring to prune the blue or pink types. These (except for the newer repeat blooming varieties) bloom on old wood. In spring only remove the dead portions. The hardy hibiscus is slow to emerge in spring. Cut them back to about a foot. I like to leave this much stem stand so I do not accidentally dig up or damage this late emerging plant. Fallopia will die back to the ground in fall. You can prune out the dead stems anytime between fall and spring. Wait to prune the Little Henry Sweetspire. Winter damage usually dictates what needs to be removed. Consider cutting back diseased or insect infected perennials in fall. Removing infested foliage reduces the source of infection next season.